Moving bulk materials from a point of origin to a final destination over short distances, typically a few miles to up to about a hundred miles, can be expensive. Bulk materials can be moved these distances by truck, rail, conveyor system, pipeline or the like. The problem can be made more difficult when the point of origin or final destination moves as the case, for example, of an advancing work face in a mine.
Some of the problems of moving bulk materials are illustrated by examples from the mining industry. Materials including ore are moved around in mining operations by a number of means including:                trucks        conveyor systems        slurry pipelines        rail transport        
Trucks have an advantage that they can go anywhere a road can be built. However, trucks, especially large mining trucks, are expensive to purchase and operate, and they usually require a driver. There are some mines that have automated trucks wherein the operator controls the truck from a remote location. Nevertheless, large mining trucks also require specialty tires and fuel, both which can be expensive.
Conveyor systems have advantages in certain mining situations where the ore and environmental situations are favorable. A major drawback of conveyor systems is that the ore or waste rock usually must be crushed. In other situations, conveyor systems can be maintenance intensive and can cause serious delays in production when they are shut down for repair. For example, ore in oil sands surface mines can be like hard rock in the winter and sticky asphalt in the hot summer months, making conveyor maintenance expensive in both seasons. Also if a section of conveyor breaks down, the whole conveyor line must be shut down until the section is repaired. Conveyor systems in underground mines can be particularly costly to maintain and repair because of the close quarters typical of most underground operations.
Slurry transport systems are suitable for ores that can be formed into a slurry. A major drawback of slurry systems is that the ore or waste rock usually must be crushed. These systems, also called hydro-transport systems, are often used in conjunction with another transport system since the slurry cannot usually be formed at or near the working face. Slurry systems are often used where transport distances are large and fixed such as for example from a slurry plant on a mine site to a remote processing plant.
Rail systems have an advantage that they are a highly fuel efficient system because of low rolling resistance. The have a disadvantage that tracks must be laid and are relatively difficult to move, for example when the mining face moves in an open pit operation. Rail systems typically involve one or more locomotives pulling or pushing a number of unpowered bulk material carrier cars. In this configuration, a disadvantage of mining rail systems is that they are limited by track adhesion considerations to grades in the range of about 3 degrees to about 7 degrees.
Small load carrying, self-powered transfer rail cars are known. The Atlas Car & Mfg. Co. of Cleveland Ohio makes electric transfer cars for steel plants, ore processing refineries and other applications. The General Electric Company has manufactured small load carrying locomotives (10 ton load capacity) in the early 1900s. Small battery powered load carrying locomotives (5 ton load capacity) have been manufactured for the explosives industry. None of these has been automated nor have they utilized multiple propulsion sources (internal combustion engines, energy storage and grid power).
There remains a need for a high capacity materials conveyance system that has: low fuel costs; low maintenance costs; flexibility to change its routing structure; and ability to negotiate steep grades of 10 degrees or more.